﻿272 
  REPORT 
  UNITED 
  STATES 
  GEOLOGICAL 
  SURVEY. 
  

  

  Until 
  the 
  summer 
  of 
  1875 
  but 
  little 
  was 
  doae 
  toward 
  the 
  exploration 
  

   of 
  the 
  localities 
  from 
  which 
  the 
  ore-bearing 
  gravel 
  came. 
  During 
  that 
  

   summer 
  many 
  hundreds 
  of 
  claims 
  were 
  located 
  on 
  lodes 
  both 
  of 
  gold 
  

   and 
  silver, 
  and 
  since 
  then 
  considerable 
  work 
  has 
  been 
  done. 
  But 
  little 
  

   however 
  is 
  known, 
  up 
  to 
  the 
  time 
  of 
  this 
  writing, 
  of 
  the 
  value 
  of 
  more 
  

   than 
  a 
  very 
  few 
  of 
  the 
  lodes. 
  The 
  Comstock, 
  which 
  occurs 
  near 
  the 
  

   foot 
  of 
  the 
  valley 
  on 
  the 
  very 
  border 
  of 
  the 
  metamorphic 
  area, 
  shows 
  

   some 
  very 
  fine 
  silver 
  ore. 
  

  

  Accompanied 
  by 
  Dr. 
  Peale 
  1 
  visited 
  as 
  many 
  of 
  the 
  located 
  lodes 
  as 
  my 
  

   time 
  would 
  permit, 
  and 
  made 
  such 
  observations 
  as 
  were 
  possible 
  in 
  their 
  

   unworked 
  state. 
  The 
  observations 
  were 
  necessarily 
  fragmentary, 
  and 
  

   speculations 
  as 
  to 
  the 
  character 
  and 
  richness 
  of 
  lodes 
  based 
  upon 
  such 
  

   meager 
  facts 
  would 
  be 
  manifestly 
  useless. 
  The 
  small 
  extent 
  of 
  the 
  

   mineral-bearing 
  district 
  may 
  seem 
  to 
  indicate 
  that 
  it 
  cannot 
  prove 
  very 
  

   rich, 
  but 
  a 
  number 
  of 
  the 
  lodes 
  show 
  considerable 
  persistency, 
  having 
  

   been 
  traced 
  many 
  thousands 
  of 
  feet. 
  These 
  show 
  fair 
  prospects 
  through- 
  

   out. 
  A 
  number 
  of 
  lodes 
  are 
  extremely 
  wide 
  and 
  show 
  but 
  little 
  ore. 
  

   In 
  some 
  cases 
  a 
  number 
  of 
  veins 
  run 
  side 
  by 
  side. 
  A 
  town 
  has 
  been 
  

   built, 
  and 
  it 
  is 
  hoped 
  that 
  increased 
  facilities 
  may 
  enable 
  the 
  sluicing 
  

   to 
  go 
  on 
  with 
  good 
  profit. 
  The 
  locality 
  is 
  one 
  of 
  the 
  most 
  enchanting 
  

   in 
  Colorado, 
  and 
  although 
  at 
  too 
  great 
  an 
  altitude 
  to 
  admit 
  of 
  agricul- 
  

   tural 
  pursuits, 
  it 
  is 
  within 
  easy 
  reach 
  of 
  the 
  rich 
  agricultural 
  valleys 
  

   of 
  the 
  Animas 
  and 
  Mancos 
  Rivers. 
  It 
  is 
  accessible 
  to 
  wagons 
  by 
  way 
  

   of 
  Tierra 
  Amarilla 
  only, 
  and 
  hence 
  labors 
  in 
  this 
  respect 
  under 
  consid- 
  

   erable 
  disadvantage. 
  The 
  settlement 
  is 
  surrounded 
  by 
  a 
  fine 
  grass 
  

   country, 
  at 
  least 
  for 
  summer 
  range. 
  The 
  mountains 
  abound 
  in 
  good 
  

   timber, 
  and 
  there 
  is 
  an 
  inexhaustible 
  wealth 
  of 
  coal 
  on 
  all 
  sides. 
  

  

  SIERRA 
  EL 
  LATE. 
  

  

  Twenty-five 
  miles 
  southwest 
  of 
  the 
  La 
  Plata 
  Mountains, 
  and 
  just 
  

   beyond 
  the 
  western 
  border 
  of 
  the 
  Mesa 
  Verde, 
  is 
  the 
  small 
  eruptive 
  

   group 
  known 
  as 
  Sierra 
  el 
  Late. 
  It 
  is 
  in 
  the 
  extreme 
  southwest 
  corner 
  

   of 
  Colorado 
  and 
  totally 
  isolated 
  from 
  other 
  highlands. 
  (See 
  Panorama, 
  

   plate 
  XXXVI.) 
  The 
  area 
  occupied 
  by 
  this 
  group 
  is 
  not 
  more 
  than 
  40 
  

   square 
  miles 
  and 
  the 
  highest 
  summits 
  do 
  not 
  reacli 
  10,000 
  feet. 
  Viewed 
  

   from 
  all 
  sides 
  it 
  appears 
  to 
  be 
  a 
  cluster 
  of 
  rounded, 
  and, 
  for 
  the 
  most 
  

   part, 
  gently-sloping 
  hills, 
  from 
  which 
  rise 
  two 
  or 
  three 
  steeper 
  cone- 
  

   shaped 
  points. 
  At 
  the 
  southern 
  end 
  is 
  a 
  double-topped 
  mountain 
  9,000 
  

   feet 
  in 
  height, 
  to 
  which 
  we 
  have 
  given 
  the 
  name 
  Hermano 
  Peaks. 
  At 
  

   the 
  northern 
  extremity 
  is 
  a 
  steep 
  symmetrical 
  cone 
  that 
  rises 
  to 
  9,900 
  

   feet. 
  This 
  is 
  known 
  by 
  the 
  La 
  Plata 
  miners 
  as 
  Ute 
  Peak. 
  It 
  is 
  the 
  

   highest 
  point 
  within 
  25 
  miles, 
  and 
  from 
  all 
  parts 
  of 
  the 
  San 
  Juan 
  basin 
  

   is 
  a 
  prominent 
  landmark. 
  The 
  entire 
  group 
  is 
  pretty 
  well 
  covered 
  with 
  

   vegetation 
  ; 
  considerable 
  forests 
  of 
  piiions 
  occupy 
  the 
  lower 
  and 
  middle 
  

   slopes, 
  and 
  clusters 
  of 
  spruces 
  occur 
  about 
  the 
  summits. 
  Grass 
  is 
  found 
  

   in 
  favorable 
  localities 
  about 
  the 
  bases, 
  but 
  sage 
  and 
  bad 
  lands 
  occupy 
  

   most 
  of 
  the 
  lowland. 
  Water 
  is 
  found 
  in 
  many 
  of 
  the 
  gulches 
  through- 
  

   out 
  the 
  summer 
  season. 
  

  

  The 
  bulk 
  of 
  the 
  mountain 
  mass 
  is 
  composed 
  of 
  trachyte, 
  of 
  which 
  there 
  

   are 
  a 
  number 
  of 
  varieties. 
  Ordinarily 
  it 
  is 
  composed 
  of 
  a 
  dark-gray 
  micro- 
  

   crystalline, 
  feldspathic 
  paste, 
  with 
  many 
  acicular 
  crystals 
  of 
  hornblende 
  

   and 
  a 
  little 
  sauidite, 
  porphyritically 
  imbedded. 
  All 
  the 
  specimens 
  col- 
  

   lected 
  were 
  found 
  to 
  contain 
  considerable 
  magnetite. 
  A 
  specimen 
  col- 
  

   lected 
  near 
  the 
  summit 
  of 
  Hermano 
  Peaks, 
  differs 
  considerably 
  from 
  

   this. 
  It 
  is 
  composed 
  of 
  bluish 
  gra\^ 
  paste 
  with 
  large 
  crystals 
  of 
  oligo- 
  

  

  